PUA - NirCmd Execution As LOCAL SYSTEM — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-01-24 / 2023-02-13.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: b5c3a775a842beefba88a49586ab88a55d42484d8c58233f82d7baa7dbdb319d

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: PUA - NirCmd Execution As LOCAL SYSTEM
id: d9047477-0359-48c9-b8c7-792cedcdc9c4
status: test
description: Detects the use of NirCmd tool for command execution as SYSTEM user
references:
    - https://www.nirsoft.net/utils/nircmd.html
    - https://www.winhelponline.com/blog/run-program-as-system-localsystem-account-windows/
    - https://www.nirsoft.net/utils/nircmd2.html#using
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2022-01-24
modified: 2023-02-13
tags:
    - attack.execution
    - attack.t1569.002
    - attack.s0029
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: ' runassystem '
    condition: selection
falsepositives:
    - Legitimate use by administrators
level: high

Original YAML and metadata in JSON

False positives

• Legitimate use by administrators

Source references

• https://www.nirsoft.net/utils/nircmd.html
• https://www.winhelponline.com/blog/run-program-as-system-localsystem-account-windows/
• https://www.nirsoft.net/utils/nircmd2.html#using